Spindle fibers play a vital role in mitosis by facilitating the separation of chromosomes into two daughter cells.

Spindle fibers, also referred to as spindle microtubules, are integral components of the cell’s cytoskeleton and are crucial during mitosis, the process through which a cell divides. Their primary function is to ensure the accurate segregation of chromosomes, guaranteeing that each daughter cell inherits an equal and identical set of chromosomes.

During the initial phase of mitosis, known as prophase, the cell’s chromosomes undergo condensation and become visible. Concurrently, the spindle fibers begin to form from a region called the centrosome, which duplicates and migrates to opposite poles of the cell. These spindle fibers extend toward the cell’s center, assembling into a structure known as the mitotic spindle.

As the cell transitions into metaphase, the chromosomes align along the cell’s equatorial plane, referred to as the metaphase plate. Each chromosome is tethered to spindle fibers from both centrosomes via a structure called the kinetochore, which is situated at the chromosome’s centromere. This dual attachment ensures that the forces exerted by the spindle fibers are balanced, maintaining the chromosomes at the center of the cell.

During anaphase, the sister chromatids—identical copies of a chromosome—separate, and the spindle fibers begin to shorten. This shortening action pulls the sister chromatids toward opposite poles of the cell, ensuring that each daughter cell will receive one copy of each chromosome.

Finally, in telophase, the spindle fibers disassemble, and the chromosomes start to decondense. Additionally, the nuclear envelope re-forms around the chromosomes at each end of the cell, signaling the conclusion of mitosis. The cell then progresses into cytokinesis, where the cytoplasm divides, resulting in two identical daughter cells.

In summary, spindle fibers are essential for the precise segregation of chromosomes during mitosis. They ensure that each daughter cell receives an identical set of chromosomes, preserving genetic continuity across generations. Without the function of spindle fibers, proper cell division would be compromised, potentially leading to genetic abnormalities and various diseases.